In reply to a post by MHC:

Even if they are not generator powered and the noise you are seeing is probably not from a "motor" (generator dynamo, alternator, compressor pump &c) there will still be the other radio and detectors to be considered which are more likely to be up in those frequency bands.

Okay, well, I'm not sure what i can do in this situation. My ISP won't take action unless sync falls below 36 Mbps.

Even if it does drop to below 36Mbps and the roadworks are to blame, what will your ISP actually do?

How long will the roadworks be there for? Can you wait and see if it recovers?

From your graphs the suggestion is that there are two specific noise sources - relatively high powered which is why there is a wide band of interference, rather than a failing card, cross talk, bad joint, worn cable &c.

Can you ask a neighbour if you could look at their line - use your modem if necessary and see if they are being hit at the same frequencies.

In reply to a post by MHC:

Even if it does drop to below 36Mbps and the roadworks are to blame, what will your ISP actually do?

How long will the roadworks be there for? Can you wait and see if it recovers?

From your graphs the suggestion is that there are two specific noise sources - relatively high powered which is why there is a wide band of interference, rather than a failing card, cross talk, bad joint, worn cable &c.

Can you ask a neighbour if you could look at their line - use your modem if necessary and see if they are being hit at the same frequencies.

If it drops below 36 Mbps then I guess there's not much my ISP can do if roadworks are to blame.

I really have no clue how long the roadworks will take but it seems to take 2 weeks per section and they move further up along the road and repeat the process.

Not sure about neighbours, not really close to them

Anyway I've reported this to my ISP and I'll see what they can do.

increase in QLN suggests to me crosstalk, shoot the neighbour who had FTTC installed

just read wombats reply.

I agree with him the QLN change is a bit unusual in that the adsl range is also affected, but in D2 and rest of D1 its typical crosstalk behaviour.

A possible issue here could be the power masking is messed up, your QLN should dip on the adsl power cut back range, and the new graph it doesnt do that, yet the bitloading is lower. That suggests you have increased noise in the adsl2 frequency which shouldnt be happening.

Edited by Chrysalis (Fri 16-Oct-15 14:49:26)

My ISP keeps saying there is no problem with the line, but surely a sudden speed decrease from 49 Mbps to 39 Mbps indicates a problem? They keep fobbing me off now with "Your promised speed is between 26mbps to 35.5mbps".

In reply to a post by smsmasters:

My ISP keeps saying there is no problem with the line, but surely a sudden speed decrease from 49 Mbps to 39 Mbps indicates a problem? They keep fobbing me off now with "Your promised speed is between 26mbps to 35.5mbps".

Old criteria (for Openreach to agree to an engineer) used to be
a) Automatic tests show a fault on the line; or
b) The speed has dropped, gradually, to somewhere below the 10th percentile; or
c) The speed drops more than 20% in one hit (within, say, a week)

I don't know if (c) remains as valid criteria, but it would certainly apply to your line.


Note 1) For (b), note that the range shown in the checker is the 20th percentile; the criteria nowadays is the 10th percentile - a much lower speed.

Note 2) The BTW dsl checker provides two ranges, one for "clean", which should apply for an engineer install, and one for "impacted" which should apply for a self-install.

What ranges does the checker report for your line? What range did the ISP quote initially? How was your FTTC connection installed in the first place?

Surely you've worded that badly?

As I see it, on a self-install there is nothing to prevent attaining or even exceeding the Clean estimate if the home wiring is fine and the master socket is used?

In reply to a post by WWWombat:

In reply to a post by smsmasters:

My ISP keeps saying there is no problem with the line, but surely a sudden speed decrease from 49 Mbps to 39 Mbps indicates a problem? They keep fobbing me off now with "Your promised speed is between 26mbps to 35.5mbps".

Old criteria (for Openreach to agree to an engineer) used to be
a) Automatic tests show a fault on the line; or
b) The speed has dropped, gradually, to somewhere below the 10th percentile; or
c) The speed drops more than 20% in one hit (within, say, a week)

I don't know if (c) remains as valid criteria, but it would certainly apply to your line.


Note 1) For (b), note that the range shown in the checker is the 20th percentile; the criteria nowadays is the 10th percentile - a much lower speed.

Note 2) The BTW dsl checker provides two ranges, one for "clean", which should apply for an engineer install, and one for "impacted" which should apply for a self-install.

What ranges does the checker report for your line? What range did the ISP quote initially? How was your FTTC connection installed in the first place?

An "engineer" (I think it was a contractor) replaced the faceplate and installed everything for me.

Back in 2013 I don't recall a range specified by my ISP when I ordered.

Back in 2013 I did initially sync at around 55 Mbits, even as high as 60 Mbits at one point.


The checker reports:
FTTC Range A (Clean) 55.3 35.7 13.9 8.3
FTTC Range B (Impacted) 46.5 27.4 13.7 6.1

Edited by deleted (Fri 16-Oct-15 22:28:39)

Perhaps a silly question but have you noticed any difference in noise during telephone calls since this happened?

I had a similar issue seeing my attainable sync drop from 120Mbps to 90Mbps over the course of a few months due to crosstalk from other customers being added to the DSLAM. Since then, the line has had a very faint buzzing sound on it. Despite having a half witted engineer out to say it was just "Normal VDSL noise" (Despite any noise being a cause for a fault), it still remains to this day unsolved.

What may have happened is an engineer connected 1 or more customers to the DSLAM who use the same D-side cable as you under the pavement which has caused a noticeable drop in sync due to crosstalk.

On the plus note if your connection drops a few more Mbps, you'll have the ability according to the figures given to you by your provider to get an engineer out to have a look at it.

In reply to a post by RobertoS:

Surely you've worded that badly?

Maybe, maybe not. It reads OK to me, but I'm tired.

As I see it, on a self-install there is nothing to prevent attaining or even exceeding the Clean estimate if the home wiring is fine and the master socket is used?

Well, given that the top of both ranges is still only the 80th percentile, there is nothing to stop speeds exceeding either range.

The real point is that a <proper> engineer installation should result in a provable clean line; the engineer should do enough work to ensure that the line qualifies as "clean". With Openreach having made sure of this (through a suitably qualified and skilled employee or contractor), they are effectively telling the ISP that they can sell the A range speed to the end-user, and are willing to stand by such estimates.

Oh ... and a "clean" line, to me, implies a lot about the quality of the line outside the house - not just the socket and internal wiring. It is the end-end quality that matters. I've had three FTTC lines installed by engineers (two Openreach, one Kellys), and all of them have taken the requisite care over this - though the latest one made use of more automated tests than the previous ones.

A self-install, by a knowledgeable and skilled end-user, can result in a line that is every bit as good as an engineer installation. However, Openreach don't know that, so are only willing to stand by a B range estimate. You won't find it easier to get an engineer to attend - and to me, that makes a self-install something of a false economy.